The following discussion of the prior art is intended to place the invention in an appropriate technical context and enable the associated advantages to be fully understood. However, any discussion of the prior art throughout the specification should not be considered as an admission that such art is widely known or forms part of the common general knowledge in the field.
Devices for emitting or receiving energy signals over a range of positions are known. One such device is the pan-tilt positioning device for a video camera. In this application the energy signal being received is an optical video signal. Typically, this device includes two motor assemblies driving a video camera about a vertical and/or horizontal axis. In this way, video signals may be received over a range of positions based on selective rotation of the motors. A disadvantage of this device is its complexity and the amount of space required to package both motor assemblies.
Another device that transmits an energy signal over a range of positions is the remote mirror module for a radar-emitting/receiving device. In this device, radio waves are emitted onto a reflective element which in turn is rotated about 360° to transmit the radio wave about this range. Returning radio waves are received and read along a reverse path. This device allows radar wave signals to be rotated about the 360° azimuth range whilst the emitting/receiving unit remains stationary. Many remote mirror module type devices are also capable of some zenith motion of the reflective element. A disadvantage of this arrangement is that the mechanism to rotate the mirror is required to be at opposite ends to the emitting/receiving unit. As a result, either the emitting/receiving unit or mirror rotation mechanism is exposed above the main support housing making it vulnerable to damage. Furthermore, having either the emitting/receiving unit or mirror rotation mechanism suspended above the other, necessitates additional support structures, which may create occlusions in the transmission and/or reading path.
Another type of device for sensing energy signals is the static array. In brief, the static array comprises a plurality of sensors disposed at various points around a frame, thereby to sense energy signals coming from various directions. Disadvantageously, since the static array is not moveable, its sensing range is fixed.
It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.
It is an object of the invention in its preferred form to provide an energy signal processing system that is relatively compact and inexpensive to manufacture and can receive or emit an energy signal about two axes.